You need to specify the length of the slope, or the length of the deep end to do it correctly, and I don't know about stairs. Assuming the deep end is 14 and the slop is 10....
Shallow end (squared off)
(37-24) x 27 x 4 = 1,404
Shallow end (Inset)
(13-3-3) x 3 x 4 = 84
Slope (assumed 10')
((4+10) / 2) x 10 x 19 = 1,330
Deep end (assumed 14')
14 x 19 x 10 = 2,660
1,404 + 84 + 1,330 + 2,660 = 5,478 cu. ft.
5,478 x 7.48 = 40,975 gallons
That is making some assumptions obviously.